There has long been a need for devices to accurately measure muscle strength and to provide data regarding changes in muscle strength of subjects on which such apparatus is used. Physical therapists, athletic trainers and orthopedic surgeons, for example, need such apparatus to accurately moniter a patient's history and to systematically test for muscle improvements.
Muscle testing is an integral and important part of a complete physical exam since it provides information not otherwise obtained that is useful in differential diagnosis, prognosis and treatment of neuromuscular and musculoskeletal disorders. A knowledge of the relative strengths of the various muscles of the body provides a foundation for rehabilitation and strengthening of the muscles in a programmed manner that will give maximum overall fitness. Knowledge of the strengths of muscles before and after administration of certain drugs such as cholinergic drugs may also assist in determining the type and nature of medications and other treatments subsequently used to treat progressive muscular weaknesses such as myasthenia gravis.